It’s a mantra as old as the hills: If I want to grow my business, I need to work more. This seems like it makes sense, but it’s dead wrong.

Entrepreneurs are value-creators and creating is a process that stresses mental muscles. Like any other muscle, our brains need time for rest and recovery to work well. Want proof? Think back to that gnarly problem you were trying to work out late on a Friday afternoon. You didn’t want to leave it until Monday (that would be irresponsible, right?), so you kept working, racking your brain for a solution. Eventually, after getting no closer to solving the problem and simultaneously becoming completely frustrated, you gave up and walked away.

When you returned to that problem on Monday morning, did you find it significantly easier to solve, even to the point of wondering why you were so stressed about it the week before? The answer depends on whether you took any real time off between Friday and Monday.

Mental rest is like a dose of super foods for your brain. Without it, you may survive, but you will never excel. We all have an awareness of this fact, but when we know that working has resulted in success, it can be difficult to impossible to choose to stop working, even if we know that doing so would be good for us.

According to Scientific American, “Downtime replenishes the brain’s stores of attention and motivation, encourages productivity and creativity, and is essential to both achieve our highest levels of performance and simply form stable memories in everyday life.”

Long-term success and sustained creativity is completely dependent on taking regular time off from work. It really is just that simple. (For a full treatise on this subject, read The Power of Full Engagement by James Loehr and Tony Schwartz.)

What is a true “day off?”Management guru Dan Sullivan of Strategic Coach defines a day off this way: A 24-hour period from midnight-to-midnight with no phone calls, e-mails, correspondence, conversations and focused thinking about work.

That’s not easy to achieve, especially when you’re in the habit of working seven days a week. But the rewards are tremendous. Try it. Try a true and total day off. Soon.

So how do you take a true day off?

1. Schedule a day off in advance. Let your family and colleagues know that you will be off the grid for a full 24 hours. They will think you’re crazy and won’t believe that you can actually step away from technology and work for that long. So be it. Ignore the doubters and stick to your plan!

2. Plan a distraction. Daily habits die hard -- you will definitely want to reach for your phone, so find a place to be that will require you to focus on something else (and leave your phone in a drawer.) In fact, plan several activities for the day such as a project around the house, going to a movie, playing a round of golf, going out for a long dinner, etc.

3. Get it out of your system. Have essential work conversations the night before your full day off. Get whatever work issues are most pressing on your mind out of your head, by doing whatever is necessary for you to be able to walk away from it all. Write a rough draft email, leave someone a voicemail, compose a to-do list. Do whatever you have to do to unload your mind as much as possible. (Don’t forget: The world will in fact keep on spinning even if you don’t check your email for a full 24 hours. Shocking, I know.)

4. Be prepared to reign in your brain. Your mind will naturally wander in the direction of work. Expect this and select some non work-related topics to put in your mental queue so that you have them at the ready when you need to switch mental channels from work to something else. Ask the friends and family you will be around on your day off to help redirect your thoughts if and when you bring up work. (People love being asked to do this!)

5. Space out. It has been proven over and over that doing nothing is, in fact, not doing nothing. Our brains are exceedingly active when we are idle. (This is what scientists call the default mode or resting state network.) When we do not choose idleness at regular intervals, we get dumber. In the same way that not sleeping adds up over time, resulting in a sleep-deficit disorder, so does not choosing to take breaks and (seemingly) space out.

You don’t have to ever take a day off. You can slog on, getting more stressed and less creative. Or, you can work smart, which means sometimes not working at all.

So go for a walk, pull out a favorite old album to listen to, chill out on the deck -- find some way to be actively idle. Your brain will thank you by working better and faster when you do go back to work.